Experience w/C4D Hair System

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  4 Weeks Ago
Experience w/C4D Hair System

I've been diving into hair the past week. The degree of control you have is remarkable. If you consider all the tools, settings and render options there might be 200 options at your command.

It's an amazing system but since it was designed a long time it doesn't take advantage of GPU acceleration nor even, I believe, of multi-thread processing. It is currently somewhat tethered to the standard renderer, because if you render w/physical or a third-party renderer the hair must be converted to polygons--millions of polygons depending on your scene.

You can't really see what you are going to get until you render...so if you are doing detailed grooming of a character you are going to be doing a *lot* of rendering. The standard renderer does this pretty eagerly and briskly. Still...it can be time consuming work for some scenes.

In this thread I'm going to post some of my explorations w/samples...and my observations.
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C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 11:55 PM.
 
  4 Weeks Ago
As I've worked through a number of tutorials there seem to be two schools of thought on work-flow.

In some cases I see the artist create hundreds of hair guides, just relying on the quick 'Add Hair' command. Other designers prefer to hand-place just a few strategic guides to control hair flow.

In my early work I've found it better to use the latter method and just control a few guides. This works well as you can optionally combine hair objects, each with different poly selections, to tailor the results you seek. Where fewer guides can be problematic is with physics. Let me explain.

By default the physics engine that allows hair to detect and collide with your scene objects predicates that detection on the guides. If you have fewer guides you can get unpredictable physics w/some individual hairs. This is particularly true when adding curl and waviness. In my case I've had a character with quite long wavy hair...and yesterday I was seeing some hair intersect right through the character's mesh, despite cranking up the physics settings. Today I will try manually adding additional guides to try to resolve the situation.

You can change the collision detection to individual hairs, but that will multiply the simulation times 5-10 times. Or more.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 10:07 PM.
 
  4 Weeks Ago
Hi I Agree with the sparse placement of quides method
particularly if one is animating hair of any real length.
this Fellow has some excellent tutorials using the sparse guides method


https://www.youtube.com/user/CGDreamsTutorials/videos


(not affiliated, merely found his video's useful for the hair system)
 
  4 Weeks Ago
In character design for gaming the most common approach is to use a low poly hair, where you rely more on material and the material's transparency to achieve a nice final result. One can still use c4d hair to build this. The general procedure is as follows:

-Use only 8-80 guide with a matching number of hair. You might get by with as few as 8-20 hairs. For this work flow each c4d hair will portray a clump or hair clusters. You will be sculpting with strips.

-In the hair object under the generate tab set it to flat, so that you are creating polygon strips

-In the c4d hair material crank up the hair thickness and use the profile spline to craft. You should now see poly strips in the viewport.

-Find a tif/psd texture of many hair strands and be sure you have a good transparency map

-Apply the hair texture, which will run the texture along those flat poly strips

-Move the hair guides around as needed and employ the grooming tools

I've just begun to play with this technique but will try to post an example of the results in this thread.

This approach can deliver results that rival using individual hairs. In some ways it might even be advantageous for non-game characters. It's fast and you can use any render engine without issue. Doing it this way is similar to how hair is fashioned in Poser and Daz.

I will add, since I'm talking game design, that a few devs have used Nvidia's HairWorks to present heavy-poly hair in real time games. Obviously Hairworks is GPU based.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 10:17 PM.
 
  4 Weeks Ago
Originally Posted by ThreeDDude: Hi I Agree with the sparse placement of quides method
particularly if one is animating hair of any real length.
this Fellow has some excellent tutorials using the sparse guides method


https://www.youtube.com/user/CGDreamsTutorials/videos


(not affiliated, merely found his video's useful for the hair system)

Yes. I've watched a number of hair tuts, including those at CGDreams channel. I liked his thinking.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 10:04 PM.
 
  4 Weeks Ago
Here is one of my tests using the "sparse guides " method
on a Daz genesis figure mesh driven by MDD data in C4D studio.
https://www.youtube.com/watch?v=KYv...eature=youtu.be

(not great I know) but better than any result I ever achieved by
simply growing the guides based on the verticies.
 
  4 Weeks Ago
Originally Posted by ThreeDDude: Here is one of my tests using the "sparse guides " method
on a Daz genesis figure mesh driven by MDD data in C4D studio.
https://www.youtube.com/watch?v=KYv...eature=youtu.be

(not great I know) but better than any result I ever achieved by
simply growing the guides based on the verticies.

Nice! If only all her hair was subject to the same dynamics I think you'd have a winner. The hair in the middle isn't moving with the rest of the hair. I'm sure you tried to achieve this but ran up against an obstacle? Were you losing your groom if you tried adding physics there?
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.
 
  4 Weeks Ago
To be honest mate,I dont remember how I set up the physics for all of the sections and never archived the scene file
One of the biggest hurdles I have encountered is the viewport performance.
Unless you cache the hair animation completey,
any attempt to move the timeline beyond frame one or the
Initial "set as dynamics ",frame bogs down the program
completely until it calculates its collisions up to the point in the timeline
where one scrolled.


This requires the constant switching of the hair object off to work on other elements in my scene.
unless I am missing something major in my understanding??.
 
  4 Weeks Ago
Originally Posted by ThreeDDude: To be honest mate,I dont remember how I set up the physics for all of the sections and never archived the scene file
One of the biggest hurdles I have encountered is the viewport performance.
Unless you cache the hair animation completey,
any attempt to move the timeline beyond frame one or the
Initial "set as dynamics ",frame bogs down the program
completely until it calculates its collisions up to the point in the timeline
where one scrolled.


This requires the constant switching of the hair object off to work on other elements in my scene.
unless I am missing something major in my understanding??.
I understand. Yes. I've been caching like a banji.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.
 
  4 Weeks Ago
Here is a screen grab (from a different program) that will help folks visualize what we are looking for with the poly hair strand technique. Now when you see this strand imagine a material with many hair fibers. Those fibers will run along our strip and be sculpted by the geo.



With strips applied on scalp:


It doesn't seem like it would look good, but if you have good texture and alpha...it's surprising.

C4D's hair system using the method above can easily create and apply these kinds of strands--with great grooming precision. You can use the all the same hair controls as well as hair physics.One can also convert to editable strips and bump into poly editing or c4d's sculpting. Here the physics can easily be applied per hair. Everything is fast and the viewport gives you a good approximation of what is going on.

One other benefit here is you can employ tools like Substance Painter and as mentioned above, more sophisticated renderers.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 10:49 PM.
 
  4 Weeks Ago
Nice to see someone having a deeper look into the hair system, glad you found my tutorials helpful.

Id like to see some collisions for hair generated geometry instances, you can use the radius set quite high which works to some extent, but its not ideal. Iv got some fair results using this method for hair cards with alphas on. In my test I rendered strips of hair with alpha passes then used this for the texture. With less guides, too few it can lead to hairs interpolating badly between the guides going through the mesh, however if you use the restrict to guides with the remove option this can sort this out.

One area which still causes me issues is the hairs lack of collisions, or at least the way in which each layer intersects causing horrible spec highlights. Having to use clones, and frizz can get rid of most but its not ideal. I would like to get hair guides from hair made in Maya into C4D to see how the guides influence this, or if its mainly down to the shader. C4D own render engines render these intersections much worse than what I use for Vray. Standard render, super fast but then it should be as it does not generate ray traced shadows, and to get any shadows you must use the light tag from the hair tags menu on a light source to get soft shadows in whcih 750 x 750 works a treat without this the hair looks flat. The flatness of the way hair is layered may also be a issue as to why intersections are happening. The hair interpolation works in a linear way from one guide to another, where as from what I see in Maya hair around a guide not linearly only between guides.

Applying guides on polygon centre of per vertex also causes this linear placement of hair. Without doubt using density maps produces the best results, and using the add guides with interpolation, radius of 0, placement of 1 lets you at least place guides in a more random way.

Dan
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C4D R19 Studio, MODO 902, Zbrush 2018, Unfold3D 9,Marvelous Designer 7, Keyshot 6 pro.
 
  4 Weeks Ago
Brushing tip:

- You can brush in different ways: tip, roots, points, guides. I suggest brushing in tips mode to get things in basic position. Then switch over to guides (or points) for precision work.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.
 
  4 Weeks Ago
Instead of using the flat guides option. One of my favorite things you can do with the C4D Hair system is use instances of a polygon as the hairs.
I had lots of fun with that one several yeas ago when the Hair option first came out.
You can edit the polygon's shape, it's material, and it's UVs and the hair system's Instances option will use that polygon object to create the hairs.
It was most fun when used with Alpha based images. That lets you create hairs from images.

-ScottA
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  4 Weeks Ago
Originally Posted by Rectro: Nice to see someone having a deeper look into the hair system, glad you found my tutorials helpful.

Id like to see some collisions for hair generated geometry instances, you can use the radius set quite high which works to some extent, but its not ideal. Iv got some fair results using this method for hair cards with alphas on. In my test I rendered strips of hair with alpha passes then used this for the texture. With less guides, too few it can lead to hairs interpolating badly between the guides going through the mesh, however if you use the restrict to guides with the remove option this can sort this out.

One area which still causes me issues is the hairs lack of collisions, or at least the way in which each layer intersects causing horrible spec highlights. Having to use clones, and frizz can get rid of most but its not ideal. I would like to get hair guides from hair made in Maya into C4D to see how the guides influence this, or if its mainly down to the shader. C4D own render engines render these intersections much worse than what I use for Vray. Standard render, super fast but then it should be as it does not generate ray traced shadows, and to get any shadows you must use the light tag from the hair tags menu on a light source to get soft shadows in whcih 750 x 750 works a treat without this the hair looks flat. The flatness of the way hair is layered may also be a issue as to why intersections are happening. The hair interpolation works in a linear way from one guide to another, where as from what I see in Maya hair around a guide not linearly only between guides.

Applying guides on polygon centre of per vertex also causes this linear placement of hair. Without doubt using density maps produces the best results, and using the add guides with interpolation, radius of 0, placement of 1 lets you at least place guides in a more random way.

Dan
good info, Dan.

I'll be doing my first density maps today. I know from a Cineversity grooming tut by Eric Reed that I can't get the hair distribution I want w/out that.

I am exploring options to get away from using Standard Render. I don't like the look of that render and don't like the old school way it handles color and specular.

A few weeks ago I had success rendering w/Octane, but with this current scene it gets stuck "preparing". I don't know if it's a settings issue, or just the higher volume of hair.
__________________
C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.
 
  4 Weeks Ago
Originally Posted by Scott Ayers: Instead of using the flat guides option. One of my favorite things you can do with the C4D Hair system is use instances of a polygon as the hairs.
I had lots of fun with that one several yeas ago when the Hair option first came out.
You can edit the polygon's shape, it's material, and it's UVs and the hair system's Instances option will use that polygon object to create the hairs.
It was most fun when used with Alpha based images. That lets you create hairs from images.

-ScottA

Hmmm... When I was looking at c4d help I saw the image here as an example. That wasn't a compelling example for me, except if I wanted hair beads or something (Could have mograph possibilities, I suppose). Maybe I should explore with something other than cones. I wish I could see some of your examples.


From c4d help:
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C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.

Last edited by IceCaveMan : 4 Weeks Ago at 11:59 PM.
 
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